Re: Vitamin D and Calcium
It might be an indication of hperparathyroidism. Your symptoms suggest it could be. ITs what I had. My calcium at its highest was around 10.8 but was enough for my doctor to order the test to see if they could pinpoint a parathyroid tumor and it was there. Its a benign tumor of the parathyroid, but if you have one it needs to be removed because it messes up your calcium regulation and leeches calcium from your bones which could lead to osteporosis. It has a whole host of other symptoms too that generally are attributed to something else.
That brain fog you describe is one, Its worth talking to your doctor to rule that out via tests.